The present invention relates to heating and cooling apparatus, and in particular but not exclusively to bench top heating and cooling plates and columns on which an object to be heated or cooled is supported thereon.
There are a number of commercial products available that can provide hot and cold operating conditions. These generally fall into two categories. The first category use Peltier elements. These electric elements are inefficient and use a lot of electricity.
In addition to being expensive to run, Peltier device based coolers are usually bulky as it is necessary to house the large, low voltage, high current units to supply the power required for the Peltier elements. Some Peltier devices also require water cooling.
Oil circulators form the second category of heater/coolers. They are bulky, have slow response times, and require pipe connections to the object being either heated or cooled. The response time can be improved by using powerful refrigeration systems though these are expensive.
U.S. Pat. No. 6,324,857 relates to a temperature controlled bath with both heating and cooling elements (20, 8) submerged within the bath fluid (3). Control of the cooling function is achieved by regulating an expansion valve (7) which controls refrigerant flow through the cooling element (8). The expansion valve is connected to a control line (9) containing a liquid. Regulation of the expansion valve is achieved by varying the temperature of the liquid within the control line using a heater (13) and refrigerant. The refrigerant is either passed through the cooling element (8) or has been introduced via a bypass line (16) downstream of the cooling element. The resulting contraction or expansion of the fluid acts to open or close the expansion valve.
U.S. Pat. No. 6,938,432 relates to a cooling apparatus in which the degree of cooling is achieved by regulating a valve (10). The evaporator maybe incorporated into a plate (15) provided with a temperature sensor (22) linked to the regulating valve (10). The refrigerant flow into the cooling element is also regulated by a further valve (5) to ensure that the refrigerant remains as a gas liquid mixture whilst in and downstream of the evaporator. This is to ensure that the temperature of the refrigerant is uniform throughout the evaporator so there is no variation of temperature across the plate. The apparatus is provided with a heater (11) downstream of the evaporator to ensure all refrigerant is in the gas phase before it reaches the compressor (2). The plate is provided with a separate heater (19) used to warm and dry the plate after a cycle of operation.